Bolster spring



April 6, 1954 H. E. TUCKER BOLSTER SPRINGS Filed Sept. 15, 1950 3 Sheets-Sheet 1 2/ 1 2 INVENTOR.

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April 6, 1954 H. E. TUCKER 2,674,449

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.DEFLECTION 7% 6g HEIGHT 0F UNIT Patented Apr. 6, 1954 BOLSTER SPRING Herbert Edward Tucker, Chicago, Ill., assignor to Cardwell Westinghouse Company, a corporation of Delaware Application September 15, 1950', Serial No. 184,936

3 Cla m 1 This invention relates to railroad car bolster springs, and has for its principal object to provide better spring support for the ends of the bolster on the side frames that will resist lateral motion or end play and return the bolster to normal position when the side thrust at a curve is gone. Generally speaking, this is accomplished with a stack of plates alternating with bars of rubber extending lengthwise to the bolster.

Fig. 1 is a side elevation of a car truck with the'end portions broken away;

Fig. 2 is a section taken on the line 2-2 of Fig. 1;

Fig. 3 is a diagram indicating how the bolster spring acts in resisting lateral motion and returning the bolster to normal position;

Fig. 4 115a perspective view of the bolsterspring, parts being broken away;

Fig. 5 is a vertical section through the bolster spring and the spring plates showing the spring at free height;

Fig. 6 is a similar view showing" the spring closed or compressed;

Figs. '7, 8, 9, and 10 are diagrams illustrating how the springs change from free height to closed; and

Fig. 11- is a diagram illustrating the hysteresis characteristics ofthe bolster spring embodying the invention.

In' Fig. l, the side frame, generall indicated by it, includes a compression member ll, a tensionmember l2, and columns 13 enclosing the familiar window opening it in which the ends of the bolster it are received and supported on springs for limited up and down movement.

The bolster and side frame may be A. A. R. standard, and the bolster should include flanges it spanning the columns l3, as shown inFig; 2, with suitable clearance at ll" for appropriate lateral motion.

In assembling the truck, the bolster end is inserted through the enlarged lower portion [8 of the window opening and raised to approximately the position shown in Fig. 1, when the supporting springs are placed beneath it.

The bolster spring of this preferred embodiment (Sheet 2) includes a stack of flat plates alternating with relatively thick and narrow rubberbars 2! arranged lengthwise to the center line of the bolster and connected by rubber through openings 22 in the plates whereby the stack is unified and held together. Preferably though not necessarily, the connection is made by moulding rubber bars and plates in place as a unit.

Associated with the stack thus described are top and bottom spring caps or plates 23 and 24 cupped at 25 near the center to cooperate with a bolt 26.

The plates 20 are provided with oblong openings 21- to receive the cup portions 25 with clear ance for movement laterally with respect to the side frame of the truck.

In one form which has been found satisfactory, there are nine relatively thin (chrome plated) steel plates 20 alternating with four sets of bars 2 I, each 10 in number, with a free height of 9% and a closed height of 6 /3 Each of the bars 2lis 1" wide with a free height, and the plates are & thick, 10 x 10 With that arrangement, the compression from free height to closed follows the diagram shown in Figs. '7, 8, 9, and 10, and in lateral motion passes through the positions indicated by the solid and dotted lines in Fig. 3.

Theconical projections 30 on the spring plates or'caps fix the top onerelative to the bolster and the bottom one relative to the side frame. Hence, when the side thrust or lateral thrust that develops on a curve produces or tends to produce lateral motion of the bolster, the stack will sway about the bottom plate substantially as shown in Fig. 3, where the dotted lines indicate the lateral motion to the left and the solid lines indicate lateralmotion to the right.

That lateral motion or end play results from the flexibility which must be provided in truck structure in order to permit easy and safe negotiation. of track curvatures. But optimum operating' conditions require that the motion be resisted, and, after the thrust is spent, the movemerit corrected so as to bring the bolster back to its proper position on straight track.

In the bolster spring of the present invention, the rubber furnishes superior resistance to the lateral motion and cushions the thrust, and also. superior correction as soon as the thrust is spent. This is a necessary incident to' the rubber bars extending lengthwise with respect to the bolster and in a stack with the plates making up the total height of the spring.

With standard A. A. R. coil springs designed for 40,000 pounds, the deflection under 10,000 pounds would be one-fourth of what it would be under 40,000 pounds; the deflection under 20,000 pounds would be one-half of what it would be under 40,000 pounds; and the period of vibration would decrease as the square of the increase in load or deflection. The result is that a light load on a standard A. A. R. coil has very little spring travel and very high vibration frequency. Hence, a car spring designed for 40,000 pounds is a very poor cushion for a load of 10,000 pounds or less.

With springs embodying the present invention designed for 40,000 pounds, a light load of 10,000 pounds would get a great deal more of deflection than with the coil springs, and there would be less change in the period of vibration. This is illustrated by the chart (Fig. 11), where the load is plotted as ordinates and the deflection as abcissae. The curve approaches a square root curve as compared to a straight line curve of coil springs.

In the case of the rubber springs, the actual deflection under a loaded car is 3" for 40,000 pounds. The efiective deflection for determining frequency is determined by drawing a line tangent 34 to the curve 35 at point 36 and projecting it to intersect the base at 32. The effective deflection is measured backwards from the 3" total deflection to the intersection 32, which gives 1%" effective deflection for determining frequency of vibration.

A load of 10,000 pounds on the same car shows an actual deflection of 1% at the point 37, and by drawing the tangent 38 to the curve 39 it intersects the base line at 40, and the effective deflection is 1%".

The advantage of this characteristic is that there is an approximate equalization of the eifective deflections for a light load and a heavy load; that is, the deflection that determines the frequency of vibration for a light load is substantially the same as for a heavy load.

When a coil spring is compressed by a blow, it stores up the energy that compressed it, and, upon release, redelivers or returns substantially an equal amount of energy. That is the keynote to spring vibration for coil springs.

When a rubber spring embodying this invention is compressed by a blow, it absorbs a large portion of the energy, which is not returned on release.

By comparison, a coil spring which will return 97% of the energy of compression would have the same capacity as a spring embodying this invention that would return only 60%.

A standard coil spring that will return approximately 97% of the energy of compression may be said to absorb about 3%. Contrasted with that, springs embodying the present invention may be designed to absorb 30, 40, or even greater per cents of the energy of compression. The energy that is absorbed is not available for rebound and vibration.

The absorption that may be had by the use of this invention is illustrated on the chart (Fig. 11) by two shaded areas marked hysteresis, which indicate that for a corresponding travel there is a greater absorption under a greater load, which distinguishes the invention from devices having a constant absorption under different loads.

I claim:

1. In a railroad car support having a bolster loosely slidable within an opening in a side frame for limited vertical and lateral movement, the improvement comprising a resilient support for said bolster mounted in said opening in spaced relation to the walls thereof, said support comprising a plurality of vertically spaced plates having aligned openings therein, a plurality of elongated, relatively narrow rubber spacing bars interposed between said plates in substantially parallel relation and extending lengthwise of said bolster, said bars being interconnected through said openings in said plates, said support having vertical and lateral components of movement to accommodate movement of said bolster.

2. In a railway car support having an upper compression member and a lower tension member interconnected by spaced upstanding columns defining a window, and a bolster spanning said window and having loose slidable engagement with said columns whereby said bolster is capable of both vertical and lateral movement, the improvement comprising means resiliently supporting said bolster on said lower tension memher for such limited vertical and lateral movement, said means comprising a plurality of generally rectangular, horizontally disposed plates spaced vertically one from another, and a plurality of elongated, relatively narrow rubber spacing bars disposed between adjacent plates in substantially parallel relation and extending lengthwise of said bolster, said resilient supporting means providing dampened horizontal and vertical components of movement corresponding to the movements of said bolster.

3. A bolster supporting spring unit comprising a stack of plates having aligned openings therein, a plurality of elongated rubber bars disposed between each pair of plates and along the outer surfaces of the end plates, said bars being arranged in substantially parallel relation to each other and having connecting portions extending through the openings in said plates to connect the stack together, upper and lower cap plates disposed outwardly of the rubber bars on the outer surfaces of said end plates, means securing said upper and lower cap plates in assembled relation with said stack, and means on said cap plates adapted to fix the spring unit in bolster supporting position with said elongated rubber bars arranged lengthwise to the center line of the bolster.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 971,415 Spencer Sept. 27, 1910 1,890,795 Spencer Dec. 13, 1932 1,924,237 Glascodine Aug. 29, 1933 1,952,102 Sproul Mar. 27, 1934 

